Response of luteinizing hormone from columns of dispersed rat pituitary cells to a highly potent analogue of luteinizing hormone releasing hormone.
The response of LH from a perfused column of dispersed rat anterior pituitary cells to LH releasing hormone (LH-RH) and the analogue, D-Ser(But)6-desGly10-Proethylamide9-LH-RH (Hoe 766), was investigated. Dose-response curves showed non-parallelism between LH-RH and the analogue. but it was evident that the analogue was considerably more potent. After a single pulse of LH-RH, LH output returned to basal values in 8 min; this was prolonged to 20 min in the case of the analogue. During this 20 min the cells were refractory to pulses of LH-RH but pulses of the analogue maintained output of LH. During constant-dose perfusion with either synthetic LH-RH or the analogue, output of LH rapidly reached a peak and then gradually fell over several hours to approach baseline values. However, a pulse of 50 mmol potassium chloride/l was still able to release LH at this time. The data are consistent with the view that this analogue of LH-RH is highly potent and is strongly bound by the LH-RH receptor. Furthermore, since it desensitizes the LH-RH receptor, it appears that continued turnover of either LH-RH or the analogue at the receptor is necessary for output of LH to be maintained.
D000818:Animals; D002064:Buserelin; D004305:Dose-Response Relationship, Drug; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D006728:Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000096:biosynthesis*; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D006728:Hormones; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D002064:Buserelin